>>> What would be the recommendation for an intermediate grammar for NT
Greek?<<<<

Have you looked at _Greek Grammar Beyond the Basics: An Exegetical Syntax
of the New Testament_ by Daniel B. Wallace, 1996, 827 p., Zondervan?

It's really very readable, and I find myself picking it up just to browse
through some of Wallace's discussion of syntactical points from time to
time. I also like the layout of the pages quite a bit. (As someone who
recently had to switch to bifocals, I find that format, layout, size of
font, and judicious use of white space are factors I appreciate more than
I used to <s>.)

I especially like that Wallace includes numerous NT examples in his
discussions of syntactical questions. His 40-page section on special uses
and non-uses of the article is especially good (and well-researched, this
was the focus of his Ph.D. dissertation).